Where can I obtain the AHT on disk for my Mac Pro 4.1?

Question

Where can I obtain a disk (iso) of the AHT for my Mac Pro 4.1 (latest OS X Yosemite) that I am busy upgrading?

Answer 1

If you can fiddle with file permissions without going nuts, the original gray discs or the downloads mentioned (once the .dmg is mounted) provide a roughly 60 to 100 MByte .diagnostics [invisible] directory at:
/Volumes/disc_name/System/Library/CoreServices/.diagnostics
You can see this folder (on the DVD or in the download) with the Finder by looking in CoreServices, using the Find command and specifying name .diagnostics and Visibility [invisible].
Open a second Finder window and navigate to the comparable place in the current Directory structure:
/System/Library/CoreServices
drag and drop the .diagnostics directory from the DVD or the download in one window to the current Core Services folder in the other window. Observe carefully to see that it actually does the copy, as Find-ing it in the current directory structure is quirky.
You may have to authenticate as Admin, or you may already have access --
-- otherwise you can change the permissions of the current CoreServices folder to allow you to Read & Write
-- don't forget to change permissions back if you modified them.
NOW try Restart and hold the D key.